Fill in the Merge Generation field with the number of the
  generation to be merged into the retrieved generation.

  The merge transaction combines two generations of an
  element and creates a single file that contains the
  annotated listing.

  The file contains text common to both generations. When
  changes that are not identical are made in the same
  position of the common ancestor, the changes from both
  generations are included in the resulting file and are
  marked as a conflict.